In advanced driver assistance (ADA) features and autonomous driving (AD) features, a control system controls the vehicle to achieve desired objectives. Examples of such objectives are to maintain the current lane, to change to a different lane, to avoid an obstacle, or to drive to a specific location while enforcing traffic rules.
The objective may be represented as a path or trajectory that the vehicle has to follow. For example, the trajectory can be generated by a decision making method, a path planner, a navigation system. In order to actually accomplish the objective, the vehicle must be controlled to actually follow the generated trajectory. For instance, the vehicle controller (VC) can receive the trajectory from, e.g., a supervisory controller (SC), and decides the steering commands that result in the vehicle following the trajectory. The VC commands are received by the actuator controller (AC), for instance in the electric power steering module, and actuated by the appropriate electromechanical devices, resulting in changing to the motion of the vehicle, in a way that makes the vehicle follow the SC trajectory. To that end, different components or layers of vehicle control, such as SC, VC, and AC, need to be properly coordinated to work together for a common objective. For example each higher layer needs to account for the behavior of the lower layer in producing its computations. Such coordination is generally difficult.
For example, in the coordination of the SC and VC, there is no guarantee that the vehicle can exactly execute the SC trajectory. This may be due to the SC using a simplified model of the vehicle motion to generate the trajectory, which for instance ignores phenomena such as longitudinal and lateral slip, or road friction, or road slope, in order to more quickly perform the trajectory computations. Also, this may be due to the presence of external factors, such as tire wear, different distance of front and rear axles from center of mass, etc., that may be unknown or not accounted by the SC. Thus, there is a need for cooperative control of different components of the vehicle having a common objective of moving the vehicle according to a desired trajectory.